Endovascular Repair of AAA

What are AAA?Management OptionsEndovascular Repair

ProcedureComplicationsPost-Operative Management

Anatomy RevisitedAbdominal aorta

Hiatus of diaphragm bifurcation into common iliac arteries (L4)

Paired and unpaired visceral branchesCommon iliac a.Internal iliac a.External iliac a.

Common femoral a (after passing below inguinal ligament)

AAA DefinitionLocalised dilatation of abdo aortaDiameter >50% of normal aortic diameter

Normal 2cm (1.4-3cm)>3cm considered aneurysmal

Up to 40% assd with iliac artery anuerysm

Indications for RepairSymptomatic

Tenderness, abdo or back painEmbolizationRupture

AAA ≥ 5.5cm>0.5cm expansion withing 6-months

Management OptionsOpen AAA repairEVARConservative

What is EVAR?Nicholas Volodos, Kiev, 1987Endovascular aneurysm repair

Folded graft components inserted through femoral artery into aorta and then deployed

Graft expands contacting the aorta wallExcludes aneurysm sac from aortic blood flow and

pressure

Suitable for 2/3 of pts with infrarenal AAA

Benefits of EVARAccounts for nearly half of all AAA repairsSignificant peri-op mortality

No open exposure or aortic clamping incidence of ruptured AAACan be offered to pts not suitable for open repair

DisadvantagesNot suitable for allCost

£3,000 - £10,000 more expensiveMay need conversion to open repairLifetime surveillance

?radiation riskDoes not completely eliminate future risk of rupture

AssessmentPre-Operative AssessmentTechnical Assessment

Pre-Operative AssessmentAs for open repairPOAC

IHD is leading cause of early & late mortalityCOPDRenal insufficency

Technical AssessmentCT angiography with 3-D reconstruction(Arteriography in emergencies)Measurements:

Aortic neck diameterAortic neck lengthAortic neck angulationInfrarenal aortic length

Common iliac a. DiameterRenal or artery anomalies

Technical AspectsAortic neck diameter

Size + 15-20% Sufficient radial forceOversize - Kinking, thrombus formn, endoleak

Aortic neck10-15mm (sufficient landing zone)Normal appearance

Aortic neck angulation<60°

Iliac ArteriesMinimal calcification / tortuosityNo stenosis or mural thrombusSufficient diameter & length

If external Iliac art. = landing zone, internal iliac art. should be embolised (prevent backflow)

Pre-Operative PreparationThromboprophylaxisProphylatic antibiotics

Cephalosporin or vancomycin for <24hrsPrevent Contrast-Induced Nephropathy

Procedure1. Anaesthetise 2. Gain vascular access3. Place guidewires & sheaths4. Confirm anatomy5. Main body deployment6. Gate cannulation7. Iliac limb deployment8. Graft ballooning9. Completion imaging

1. Anaesthetise GA, regional, LA with sedation

2. Gain vascular access Bilateral femoral access Surgical cutdown or percutaneous

3. Place guidewires & sheaths4. Confirm anatomy

Aortography

5. Main body deployment Proximal radiopaque markers Below renal artery

6. Gate cannulation Guidewire through contralateral femoral vessel Into graft gate

7. Iliac limb deployment (bilateral)8. Graft ballooning

Angioplasty of attachment sites and endograft junctions

9. Completion imaging Renal artery patency & exclude endoleak

Post-Operative CareWard careEat & drinkAnalgesiaIV fluids (prevent contrast nephropathy)D1 – mobileLOWER LIMB PULSE MONITORING

SurveillanceContrast CTADuplex US

1 month12 monthAnnual thereafter

ComplicationsRenal damage

IV contrast, emboliDVT/PE

5.3% develop DVT despite thromboprophylaxisMILower limb ischaemia/emboliEndoleak

ComplicationsOverall complication rate ~ 10%

Device-related Open conversion (<2%)

30-day all cause mortality:1.6% vs 4.8% (all)4.7% vs 19.2% (ASA IV)

3-4 year mortality equal

EndoleakType Aetiology

I Incompetent seal at proximal (Ia) or distal (Ib) attachment sites- Ongoing risk of rupture, correct promptly

II Flow into and out of aneurysm sac via patent branch vessels (lumbar, IMA)- 10-25%

III Separation of graft components (IIIa) or fabric tear (IIIb)- Ongoing risk of rupture, correct promptly

IV Egress of blood through fabric pores

V Continued aneurysm sac expansion without demonstrable leak

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